How do you get the CBLoL 2014 - paiN Gaming?
It was sold in the League of Legends store. Riot's description in the client reads: “This icon was released in the store for purchase during the 2014 esports season.”
Is the CBLoL 2014 - paiN Gaming still available?
Probably not. Riot tied the CBLoL 2014 - paiN Gaming to 2014 (store purchase), and it does not normally bring back past event rewards or bundles.
